Yamaha DTXpress/DTXplorer/DTXtreme

No problem with Yamaha sending a warranty replacement clamp for the 
one that is frozen, other than it will take 3-4 weeks thru my dealer.

I think I know what the problem is.  Since I take down my set every 
Wed and Sun and take it to church to use and then bring it back home, 
I am using those clamps a lot more than most people.  Yesterday I 
unscrewed them all and noticed some evidence of stripping beginning 
on some screws.  I then put wd40 on all and they are much smoother to 
turn.  I suspect that constant retightening 4 times each week to 
about the same point on the screw threads definitely stresses the 
threads.  And, if they are not high quality steel, stripping is only 
a matter of time.

I hope this info can be helpful to some users.

Bill